There are also human beings that are, due to genetic defect, blue-skinned--that said, hereditary methemoglobinemia is pretty rare (maybe 50 cases on record). Be

There are also human beings that are, due to genetic defect, blue-skinned--that said, hereditary methemoglobinemia is pretty rare (maybe 50 cases on record). Because of such low incidence rate, it would be silly to claim that it was worth considering when describing the human skin color spectrum. Also, the Quigley scale is useful for describing intersex people--it is designed specifically to model characteristics of a subpopulation whose size might be be negligible. Without numbers or studies, I can claim with the same accuracy that the majority of people have either a functioning penis or vagina (though, in the interest of the anatomically minded, a many of the structures are of course related). I'm merely suggesting that it'd be helpful in these discussions to have some studies backing up our assertions.